The root posets for the Dynkin diagrams are very important in many parts of mathematics, but are still very mysterious objects. In case we deal with Dynkin quivers (thus, we select an orientation of the Dynkin graph, or, equivalently, a Coxeter element of the corresponding Weyl group), there is the Auslander-Reiten quiver with its hammocks, which provides a combinatorial model of the module category. We will show that there is a strong relationship between the root posets and the hammocks.